Preheat the oven to 375°F and spray a baking sheet with cooking spray.
Form Crust & Coating
Unroll both pie crusts. Brush one side of each crust circle with 2 tablespoons melted butter. Stir sugar and cinnamon in a small bowl and sprinkle over the brushed side. Flip circles and brush the other side with the remaining melted butter.
Use a 4-inch round cutter to stamp out 12 circles.
Lightly whisk the egg and water to make an egg wash and set aside.
Assemble & Bake
Place 6 circles on the baking sheet. Divide blueberry pie filling evenly among them, mounding about 1 tablespoon per circle. Top each with 2 mini marshmallows.
Cover with the remaining 6 circles and seal edges using a fork crimp.
Brush the tops with egg wash and bake for 15–17 minutes until edges turn golden and filling bubbles.
Let pies rest on the sheet for 5 minutes before serving.
Notes
Prep testing note: chilling the cut circles on the sheet for 10 minutes helped keep edges crisp.Cooking testing note: I nailed the marshmallow puff at exactly 16 minutes.Storage testing note: cooled pies stored in an airtight container at room temperature remained crisp for 2 days.
Nutrition
Serving: 1pieCalories: 240kcalCarbohydrates: 31g
Keyword blueberry hand pies, Boo-Berry Pies, Halloween treats, hand pies, marshmallow desserts